The following principal lines of research have developed at the University of Chile as part of these cooperative efforts: (1) Unitary analysis of the auditory system at several levels of the pathway from spiral ganglion cells to cerebral cortex. Cat and rabbit have been used mainly, but comparative studies are to be done on rat and several Chilean species of rodents. (2) Unitary analysis of the visual system of the rat, including the study of: a) the oculomotor (vestibular nystagmus) influence on cell discharges at various levels of individual cells in the primary and extra-primary (peristriate) visual cortical areas which have been defined under this grant; c) the anatomical connection patterns of these areas (cortico-thalamic, cortico-cortical and cortico-collicular). (3) Behavioral studies concerned with: a) the correlation analysis of DC cortical potentials with some physical parameters of instrumental response (monkey); b) neocortical function in temporal patterns of responding produced by positive and negative reinforcement schedules (rat); c) functional significance of visual peristriate areas as defined under this grant. (4) The fourth area of research is concerned with anatomical studies that include: a) the histogenesis of the central nervous system of rabbit with autoradiographic techniques; b) the relationships among various structures of the central nervous system using Nauta techniques to complement the auditory, visual and behavioral studies; c) comparative anatomical studies of the visual system of chilean rodents, including Octodon degu. For stimulus presentation and data analysis, a LINC computer is employed.